Improvement in the manufacture of coal-gases



UNITED STATES JOHN A. BASSETT, OF SALEM, MASSACHUSETTS, ASSIGNOR OFONE-HALF HIS PATENT OFFICE.

RIGHT TO HENRI L. STUART, OF NEW YORK CITY.

IMPROVEMENT IN THE MANUFACTURE OF COAL-GASES.

Specification forming part of Letters Patent No. 118,579, dated August29, 1871.

To all whom it may concern:

Be it known that I, JOHN A. BASSETT, of Salem, in the county of Essexand State of Massachusetts, have invented certain Improvements in theManufacture of Illuminating-Gas, ofwhich the following is aspecification:

The nature of my invention consists in carbonizin g coal for makingilluminating-gas by a continuous process, in which the coal, after beingfinely pulverized, is continuously and automatically introduced into aheated chamber and the products of the destructive distillationcontinuously withdrawn. The first part of my invention relates to thedevices by which this result is aecomplished. The second part of myinvention relates to the means used for purifying the gas made in themanner set forth.

In carrying my process into effect I make use of the apparatussubstantially in the form shown in the drawing annexed to thisspecification, in which Figure 1 represents a vertical section of thegenerating apparatus. Fig. 2 represents a vertical section of thepurifier. Fig. 3 represents a plan of the same. Fig. 4 represents asection of the seal used in the purifier to connect the parts.

Similar letters of reference indicate like parts in all the figures.

A represents the retort, which I prefer to make of clay, cylindrical insection, and in lengths of two feet or more, as shown in the drawing. Itmay be made of any suitable length-not less, however, than is necessaryto make the coal incandescent in its passage from the top to the bottom.The retort should be made in such a manner and of such materials as willbest enable it to withstand the highest temperatures and allow of aproper degree of expansion without injuring the joints between eachsection. I prefer, in making it of clay, to use a large proportion ofburned refractory material, ground carefully and mixed with a smallproportion of new clay. The sections may thenbeplaced in position andburned in the furnace in which it is to remain permanently. In thedrawing the body of the retort within the furnace is shown as made ofclay, in sections, and the top and bottom, outside the heating-surface,are made of cast-iron. The section of the retort A above the furnace isunited to the body of the retort in any suitable manner and holds andsupports the apparatus for lcharging the coal.

To the top of the retort A is iitted a cast-iron ring, B, which coversthe retort and extends down over the side, fitting over the retort Awith a ground joint. It revolves upon rollers which run upon a serratedsurface, so that a jarring motion is given to the ring and thecoal-po\\"der, which is delivered through a coneshaped grating forming apart of the ring, and distributes the coal uniformly around theperiphery of the ring, in close contact with the interior of the retort.Above this ring is placed the hopper C, which contains the coal-powder,the supply of which is controlled bythe valve D, operated from the topof the hopper by the lever, as shown in the drawing. The lower part ofthe retort, outside the furnace, is also made of cast-iron, and supportsthe main body of the retort in the furnace. The outlet-pipe Ecommunicates with the exhauster and purifiers. F represents the elevatorfor conveying the crushed coal to the hopper C. rIhe ring B is revolvedby the belt B', which receives motion from the pulley which actuates theelevator F. The coke falls down through the ret-ort into the water-sealG upon the endless belt H, from which it is conveyed by the elevator Ito the furnace J. K represents a steam-boiler, which may be heated bythe waste heat of the furnace. From this boiler steam is ta-ken throughthe superheater L and injected into the retort at M. This drawingindicates an apparatus in which the retortor generating-chamber is fromthirty to fort-y feet in length and from fifteen to eighteen inches indiameter. The other parts of the appara-tus are made of a size tocorrespond with these dimensions. In this apparatus the conditions whichare recognized by those skilled in the art as essential to the perfectelimination of all the gas from the coal, for preserving itsilluminating power unimpaired, and producing the minimum of liquidproducts, are fully maintained. It is necessary for the success of thismethod ot making gas that the coal should be reduced to an impalpablepowder, and there are various means by which this result may beattained, which are well known and do not require a description in thisconnection. Other methods may be used for introducing the coal at thetop of the retort. It may, if desirable, be introduced directly from thecrushing apparatus, which may be placed above the level of the top ofthe retort for this purpose. But the plan indicated will be saved. Thefurnace is arranged so as to make to form a chamber at this point inwhich is an Which is best adapted for producing liquid hyfound to worksatisfactorily in practice, asA the quantity of coal admitted can bemore perfectly regulated and controlled. It may also be desirable toremove the coke by other means than* that shown in the drawing; but withthe apparatus devised, in connection with the peculiar form of furnaceshown, the fine coke is more perfectly taken care of and charged intothe firespace, and much expense for labor in stoking is a largecombustion-chamber, and the coke, as it burns, moves slowly down aninclined plane perforated with suitable openings arranged to admit airfreely to the burning fuel. This furnace may be on one or more sides ofthe retort-chamber, and it may be desirable, in the use `of a very longretort, to have two or more furnaces placed one above the other, for thepurpose of heating the retort more perfectly. Itis necessary that theoutlet-pipe for the gas should correspond very nearly to the shape shownin the drawing. It should have an inclination relatively to the base ofthe retort, in order that if the fine coke is drawn into the outlet withthe current of gas it will fall back into the seal, and not pass intothe condenser and purifier. It may be desirable apparatus which willshower the current of gas with water so as more perfectly to free itfrom particles o' coke. The setting of the retort in the furnace isarranged so that the lateral supports come at the level of the joints inthe retort and assist in deflecting and distributing the heat uniformlyover the whole exterior surface of the retort, and the outlet-fines arearranged with suitable dampers so as 4to allow the heat toV passdirectly to the chimney or to be deiie-cted so as to heat thesteam-boiler. The steam from the boiler is conducted through a suitablesuperheater, by which it may become highly heated, equal, at least, to atemperature necessary to decompose the coal-dust, and is used, eithercontinuously or at intervals, whenever it may be difficult to conductsufficient heat through the walls of the retort to the interior, orwhenever a very rich coal is used a quantity of hydrogen resulting fromthe decomposition of the steam Ymay be mixed with the richer gasesderived from the coal. It is also used to accelerate the motion of thecoal-dust in its passage through the retort. In either case it isessential that the steam should be highly heated, and sufficientsuperheating surface should be provided to accomplish this result.

A brief synopsis of the rationale of the present process now in use forearbonizing coal for gas purposes is necessary at this point for a morecomplete elucidation of the novel features involved inthe presentapplication. In roasting the coal in mass in a horizontal retort thecoal is acted upon bythe heat gradually; and while the exterior layer isacted upon by a very intense heat, which decomposes the light-givingconstituents into solid carbon, leaving only light carbureted hydrogenand carbonio-oxide gases, the intericr of the mass is slowly distilledat a low heat,

drocarbons, which are condensed and lost-that is, so far as theiravailibility or use in the gases is desired. A large amount of tar isproduced,

alyzed, contains as much, and in many cases more, of light-givingproperties of the coal as the gaseous products of distillation derivedin this way. This objectionable feature of the present condition of gasmanufacturing is entirely avoided.

By the method here proposed the coal is nel'y divided, and each atom isimmediately subjected to the proper heat to convert it into a permanentgas. there is no hydraulic main or seal, and the gas is withdrawn asfast as made, it does not deteriorate in photometric value by beingretained in a sluggish movement in contact7 under pressure, with ahighly-heated surface until all or nearly all of the valuablehydrocarbon v'apors are decomposed and lost. equality of the heat duringthe carbonizingprocess the chemical changes in the destructivedistillation of the coal give rise to a variety of deleteriouscompounds, which occasion great expense for purification; The number ofthese compounds and their complex character are reduced and modiiied bythe instantaneous evolution of the coal into a permanent gas without theintermediate changes which take place at low or unequal heats. Theopening of the retorts at. intervals of from four to six hours forwithdrawing the retort is not exposed to the unequal expansion andcontraction and the introduction of air resulting from this cause.

The conditions for the economical and successful manufacture ofilluminating-gas from coal are secured by this method of operation, andtheadvantages may be stated as follows: First, the process is continuousand uniform in its results. Second, a larger quantity of gas, having agreater photometric value, is produced by this method than any beforedevised. Third, the coal is uniformly acted upon by the heat, eachparticle in detail. Fourth, the gas, as soon as eliminated, is withdrawnfrom the retort without further decomposition. Fifth, all thelight-giving properties of the coal, are obtained in the form of gaswithout the production of liquid hydrocarbons. Sixth, the' expense ofpuriiication is reduced. Seventh, the apparatus is compact, nearlyautomatic, and does not depend to any large extent up on skilled laborfor the production of a uniform quality of gas, and the plant requiredto generate a given quantity of gas is reduced in size and expense.Eighth, the lower grades of coals from Nova Scotia and elsewhere areused successfully to produce gas of proper photometric value without theadmixture of the more expensive cannels now so necessary and so muchused.

The second part of my invention'relates to the purification ofilluminating-gas, and this part of the invention may be used inconnection with the apparatus herein shown and described or with theordinary method of generating gas 5 and consists in a process by whichthe lime or other mawhicln as has been'carefully estimated and an-` Thegas -is eliminated instantly, and, as

In consequence of the incoke and charging with coal is avoided, and theteri al used for purifying is automatically charged into a chamber uponrevolving perforated screenplates, through which the gas passes, and thelime, as it becomes charged with the impurities, is gradually withdrawn.

O represents the lime-chamber, which is made of wrought-iron plates orother suitable material. It is supported upon the columnsP at a suitableheight, so that the spent material may be conveniently taken away. rlheperforated screenplates R are mounted on a shaft and revolved by meansof a gear and pinion, the 'gear being attached to the top screen-plateand the pinion working inr the water-seal S, which unites and makes agas-tight joint between the top and body of the apparatus. The liniepasses from the hopper T down into the chamber U, which is madegas-tight by the slidevalvcs V, which are e11- cased in a gas-tightcasino'. The upper valve being opened and the lower valve closed, tl iechamber U is filled with lime from the hopper. The upper valve is thenclosed and the lower valve opened and the lime passes down to thescreen, which conveys it to the lower chamber; and from this it may betaken when the chamber is full and removed by the same valve arrangementas is used at entering. The gas-inlet X is a concentric opening passingentirely around the circumference of the purifier, opening into theinterior so as to secure a thorough diffusion of the gas. It isdelivered in the same manner through the outlet-pipe Y. A slow andgradual revolution is given to the screen-plates, so that the lime, asit becomes impregnated with the impurities of the gas, is constantly.being removed. The lime is constantly in motion and is presenting freshsurfaces in contact with the passing current of gas.

A less quantity of purifying material is used, the gas is brought intomore immediate contact with it, and the labor of opening and closing thepuriiier, removing the spent material, and filling with fresh lime \isalmost entirely dispensed with.

I claim as my invention- I. The manufacture of illulninating-gas fromcoal by the continuous process, substantially as is herein shown and setforth. l

2. In carrying the above-named process into eeet, an apparatus in whichthe coal is automatically charged into the retort and the coke isautomatically withdrawn, in the manner set forth.

3. In carrying the abovenanied process into effect, a vertical retort,having a water-seal which communicates with an automatic apparatus forremoving the coke.

4. In carrying the above-named process into effect, the combination,with a vertical retort, of a charging apparatus, which is constructed soas to deliver and regulate the coal to the retort, substantially as setforth.

5. In carrying the above-named process into effect, the method ofcarhonizing and decomposing disintegrated coal by the employment ofhighly-heated steam in a vertical retort, substantially as described.

6. Purifying illuminating-gas by means of an automatic apparatus inwhich the purifying material is retained between perforatedscreenplates, which receive a progressive motion in the reversedirection to the current of gas passn g through the purifying-chamber.

7. A purifying apparatus, in which the fresh purifying material isretained in a close chainher communicating with the purifying-chamber bymeans of valves7 so that the apparatus may be charged without stoppingthe action of the puri` fier or loss of gas, and in which the spentmaterial is removed in a similar manner.

JOHN A. BASSETT.

Witnesses:

EMIL VossNAcK, H. L. STUART. (38.)

